Einstein walks on an escalator at a rate of 5steps per second and reaches the other end in 10 sec. while coming back, walking at the same speed he reaches the starting point in 40secs. What is the number of steps on the escalator?

a)40 b)60 c)120 d)80 e)data insufficient

• Let the speed of escaltor be X steps per sec.
  And length of escalator be Y.
  Einstein's speed = 5 step/ sec
  
  Then,
  During upward movement
  5-X=Y/10
  
  During downward movement
  5+X=Y/40
  
  By solving equations we get Y=80.
• 8 years agoHelpfull: Yes(34) No(6)
• Correct it if I am wrong....
  
  Here whatever the speed, Distance is constant...
  
  This is based on boat and stream type.
  
  solution:-
  
  speed of moving = 5 steps/ sec
  Time taken = 10 sec
  
  clearly in question given that it takes less time in going than returning.
  
  Return time = 40 sec
  
  lets speed of escalator = y steps / sec
  
  so, distance= speed X time
  speed of moving forward = (5 + y) steps / sec
  speed of moving returning = (5 - y) steps / sec
  
  Hence , (5+y) X 10 = ( 5 - y) X 40
  => (5+y) X 1 = ( 5 - y) X 4
  => 5 +y = 20 - 4y
  => y + 4y = 20 - 5
  => 5y = 15
  ie.. y = 3
  
  now total speed of moving with escalor = 5 + 3 = 8 steps /sec
  
  Total steps = distance
  = 8 *10;
  = 80 STEPS
  
  so D is right ans
  
  
• 8 years agoHelpfull: Yes(28) No(0)
• let speed of escalator is x steps per second.
  when einstein walks same direction of escalator then his speed will be (5+x) steps per second.
  when einstein walks opposite direction of escalator then his speed will be (5-x) steps per second.
  
  so,
  10*(5+x)=40*(5-x)
  => x=3
  number of steps=10*5+10*3=80
  ans is option (d ) 80
• 8 years agoHelpfull: Yes(7) No(0)
• let einstein speed be S and escalator speed be s..
  then,a/c to question
  and no. of steps be the distance travelled by einstien is x so..
  (S+s)*10=x
  (S-s)*40=x
  then equate both equation,
  we the value of s(speed of escalator)=3
  speed of einstien is given as 5
  so put both value in any equation..
  ans-80.
• 8 years agoHelpfull: Yes(5) No(0)
• let the total step be T
  and escalator speed be S
  T/(S+5)=10
  S=T-50/10
  then from second data
  T/(S-5)=40
  now putting value of S
  T=40(T-50)/10 - 200
  3T=400
  T=133.33
  is the answer
  
  
• 8 years agoHelpfull: Yes(3) No(8)
• 5=t/10 +t/40
  5=5t/40
  t=40
  
  ans) a
• 8 years agoHelpfull: Yes(1) No(7)
• Average age of 11 players at present= x(let), then
  
  Sum of their ages= 11x ⇔ Sum of their ages 3 years back= 11x - 33
  
  Sum of current age of 3 outgoing players= 3×33= 99
  
  Sum of their current age after deducting ages of 3 outgoing players= 11x-99
  
  Let, sum of ages of 3 newcomers = N
  
  Now, new sum = 11x - 99 + N
  
  As per question,
  
  11x - 33 = 11x - 99 + N
  
  ⇒ N = 66
  
  ∴ Average of 3 newcomers = N/3 = 66/3 = 22
• 6 years agoHelpfull: Yes(1) No(0)
• Data insufficient
• 8 years agoHelpfull: Yes(0) No(11)
• data insufficient becoz there is nothing to be said about the escalator.
• 8 years agoHelpfull: Yes(0) No(12)